Radial pump or motor



United States This invention relates to high pressure, high speedrotary, radial-piston hydraulic pumps or motors, and consistsparticularly in novel piston construction for reducing inertia forcesand friction set up during operation of the pump.

Hydraulic machines of this type, as heretofore designed, have beenlimited in their operating speed and, therefore, capacity principallybecause of the very great centrifugal forces set up and the resultanthigh frictional resistance.

Frictional resistance and wear are further increased due to improperlubrication of the pistons and reaction parts. The problem results notonly from the great radial and torsional forces transmitted betweent hepistons, cylinder body, and reaction parts, but also from the tendencyto suck lubricant away from the bearing surfaces during the suctionstrokes of the pistons. An inadequate lubricant seal around the pistonsmay, also, permit sucking of air into the cylinders, resulting in noisyoperation and vibration, frequently leading to premature failure.

Consequently, an object of the present invention is to provide a pump ofthe radial piston type which is capable of higher speed operation and,therefore, greater volumetric capacity than previous pumps.

Another object is to provide for improved lubrication, particularly, ofthe pistons and reaction ring parts in this type of pump or motor.

Another object is to provide a rotary, radial piston type of pump ormotor having substantially less piston mass and, accordingly, lessinertia forces than previous devices of this type. 1

Another object is to simplify and cheapen a radial pump or motor of thistype by reducing the inertia forces set up during operation and,therefore, the necessary ruggedness of reacting parts and bearings.

Another object is to provide a rotary pump of the radial piston typehaving increased efficiency.

Another object is to provide a pump of this type with means to reducethe tendency of gas and air bubbles to form in the cylinders, andresultant noisy operation and vibration.

These objects and other more detailed objects hereafter appearing areattained by the novel structure illustrated in the accompanying drawingin which FIG. 1 is a horizontal central section through the device;

FIG. 2 is a vertical transverse section taken substantially on thecorresponding section line of FIG. 1; and

FIG. 3 is an enlarged detail showing one of the novel pistonsdisassembled.

According to the present invention, the radially reciprocating pistonsare hollowed longitudinally therethrough so that the operating liquidextends in solid columns from the spindle valve to the reaction ring forlubricating the reaction bearing surfaces and transmitting substantialportions of working forces independently of the pistons. Thus the massof the pistons is substantially reduced. Within the pistons are providedoutwardly opening check valves which open during the pressure strokes ofthe pistons and close during their suction strokes to isolate bodies ofliquid under pressure about the reacting surfaces of the pistons andreactance ring structure.

The pump is mounted in a stationary, main casing 10, of generallycylindrical contour, having an integral end wall 11 upon which ismounted an attachment block 12 7 atent 3,0533% Patented Nov. 13, 1962for hydraulic fittings, one being shown at 13. A cap 14 closes the otherend of the casing and is provided with a ball bearing 15 which receivesjournal 16 on drive shaft 17 extending through the cap. At the inner endof the drive shaft is a flange 18 having a central cup 19 and bolted, asat 20, to the cylinder body 21. Concentric with shaft 17 and extendingthrough the body from fitting block 12 is the valve spindle 22, havingan enlarged extremity 23 press fitted in casing end wall 11 and providedwith diametrically opposite operating ports 24- and 25. Longitudinalpassages 26 and 27 extend from block 12 through the valve spindle andcommunicate with ports 24 and 25.

The central, cylindrical part of the cylinder body is received upon andmaintained at operating clearance with respect to spindle valve 22 bymeans of needle bearings 2% and 29 which accurately maintain theconcentricity of the cylinder body and valve. Cup portion 19 on thedrive shaft maintains bearings 28 in position. A fitting 30 in the endof the drive shaft mounts a spring pressed relief valve which holdsliquid in space 31 at sufficient pressure to properly lubricate bearings28. Excess pressure is delivered to the casing through a passage 33.

Radiating from the spindle valve in a plane normal thereto and cuttingthe axes of ports 24 and 25 are cylinders 34- which, during rotation ofthe cylinder body, sequentially communicate, respectively, with ports 24and 25 for alternately pressuring and discharging the cylinders. Workingin each cylinder is a piston 35 having a T-head 36. The flat outersurfaces of all of the heads 36 slidably engage inwardly facing, chordalbearing surfaces 37 on the sectors 38 forming part of the reaction ringstructure. Snugly received about and positioning sectors 38 is a ring39, the ring and sectors being clamped between circular side pieces 49secured together by bolts 41. Sectors 38 also have ribs 37a locatedradially inwardly of and paralleling surfaces 37. These ribs underliepiston heads 36 so as to enforce outward movement thereof during thesuction cycle.

The reaction structure is rotatably carried within an adjusting ring 42by means of roller bearings 43 and 44 lodged within corner cutoutsprovided therefor in the side pieces. Adjusting ring 42 hasdiametrically spaced pads 45 and 46 which slidably engage milled bearingsurfaces 47 and 48 within casing 10 for guiding the reaction ringstructure in linear movements transversely of the casing. A pin 49,between pads 45 and 46, projects laterally from the adjusting structurethrough a packed opening 50 in the casing wall. A bolt 51 projects fromring 42 oppositely of pin 49 and its threaded extremity receives anadjusting wheel 52 sealingly received in a packing box 53 secured to thecasing wall about opening 54 therein. Turning of wheel 52 shifts thereaction ring structure to vary its eccentricity relative to thecylinder body and, consequently, the piston stroke.

The pistons have hollowed interiors extending longitudinallytherethrough, as best shown in FIG. 3, each including an outer portion55 and an enlarged, internally threaded inner portion 56 receiving avalve seat member 57 having a polygonal wrench receiving opening 58 atits inner end and a tapered outer end opening 59. A spider 60 lodgedacross the tapered end of the valve seat member retains a check ball 61in position relative to its tapered valve seat.

In operation, as a pump, hydraulic pressure lines are connected to theproper fittings in block 12 in a manner to connect the valve ports,respectively, to the pressure and suction sides of the hydraulic systemand wheel 52 is properly adjusted to determine the piston stroke. Poweris supplied to drive shaft 17, causing rotation of cylinder body block21 and the reactance ring structure 38, 39 and 40. If the reactance ringstructure is in an operative position eccentric of the cylinder block,the pistons will be caused to reciprocate within their cylinders andheads 36 will oscillate between chordal bearing surfaces 37 and 37a onthe reactance structure, thus pressuring the hydraulic system. Normally,the space between the cylinder body and the reactance ring structurewill be maintained full of operating liquid due to centrifugal force andleakage past the pistons. During the outward or suction strokes of thepistons, check balls 61 will be held tightly on their seats so as toisolate the bodies of hydraulic liquid within the hollowed interiors ofthe pistons, thus trapping this body of liquid in position to insurecontinued lubrication of the reactor bearing surfaces and preventing thesucking of lubricant away from the cylinder walls. This is particularlyimportant since transmission of pump torque through the pistons causesthe application of substantial lateral forces between the pistons andcylinder walls. This trapped body of liquid also tends to prevent theformation of gaseous bubbles in the cylinders, during the suctionstrokes which would result in shocks and noisy operation. A furtheradvantage of the check equipped, hollowed interiors of the pistons isthat when the stroke is reversed from the suction to the pressure cyclea body of solid liquid is immediately available for transmitting pumpforces from the reactance structure to the liquid in pressure passages26.

After the cylinder body travels 180 during the suction strokes ofcertain of its pistons, the directions of these pistons will be reversedand their associated cylinders connected to pressure port 24. At thistime, check balls 51 will leave their seats so that a continuous columnof liquid will exist between each associated reaction bearing surface 37and the pressure passages, thus transmitting substantial portions of thepumping pressure directly from the reactance ring to the pressure port.

The hollowed construction of the pistons servesto substantially reducethe mass thereof so that centrifugal forces during high speed operationof the machine are substantially reduced. Accordingly, the pump may beoperated at higher speeds than where the pistons are of solidconstruction. Furthermore, since substantial portions of the pumpingforces from the reactance ring structure are transmitted independentlyof the pistons, the pistons themselves need be only rugged enough tocarry the remainder of such forces. Consequently, the pistons may bemade of substantially lighter construction and, in fact, constitutemerely the shells of cylinders.

As previously explained, the check valves 61 serve an important functionduring the suction stroke in that they prevent the application of pumpsuction to the reactor bearing surfaces which would tend to withdrawlubricant 5. therefrom and to introduce air or gaseous bubbles into thecylinders.

Thus, the novel hydraulic machine, particularly when used as a highpressure hydraulic pump, is able to operate at higher velocity thanprevious pumps of this type, so that greater volumes may be pumpedwithout loss of pressure. Furthermore, the pump operates moreefficiently, particularly during the suction stroke thereof and withless danger of the introduction of gaseous bubbles into the cylinders.By the use of the present invention, a pump of usual proportions forservice in a high pressure hydraulic system, may be designed to pumpover gallons per minute at 3,000 psi. The necessary high speed andreduced frictional resistance are made possible by the novel, partiallycounterbalanced piston construction.

The invention may be modified in various respects as will occur to thoseskilled in the art and the exclusive use of all modifications as comewithin the scope of the appended claim is contemplated.

In the claim:

In a rotary, radial piston pump or motor, a rotatable cylinder bodyhaving an internal pressure chamber and at least one cylinder radiatingtherefrom, a reaction ring received eccentrically about said body, apiston working in said cylinder and having bearing means at its outerand slidably engaging said ring, there being a chamber extendinglongitudinally through said piston from end to end thereof and occupyinga major portion of the volume of said piston so as to substantiallyreduce the weight thereof, a valve seat located intermediately in saidpiston chamber and communicating with said cylinder and said chamber,and an outwardly opening check valve on said seat for providing directfluid communication between said pressure chamber and said ring totransmit a substantial portion of the working fluid force directly tosaid ring during the pressure stroke of said piston and to lubricatesaid bearing means while cutting off said communication during thesuction stroke to trap a body of fluid between said valve and said ringand prevent the sucking of air and lubricant inwardly across saidbearing means.

References Qited in the file of this patent UNITED STATES PATENTS1,152,729 Hele-Shaw Sept. 5, 1915 2,250,512 Vickers July 29, 19412,429,011 Wylie Oct. 14, 1947 2,518,578 Tomlinson Aug. 15, 19502,687,615 Morrow Aug. 31, 1954 FOREIGN PATENTS 745,216 France May 8,1933 764,698 Great Britain J an. 2, 1957

